In the past, there has been proposed a remote measurement system configured such that energy meters measure energy consumptions in facilities and a master (master terminal) periodically obtains measurement results as meter-reading data from slaves (slave terminals) attached to the energy meters (see document 1 [JP 2011-250301 A]).
In the system disclosed in document 1, the master communicates with an upper server (upper aggregation server) through a communication network. The upper server may be operated by an electric power company. The master obtains the meter-reading data of the individual energy meters from the slaves, aggregates to form meter-reading information, and sends the meter-reading information to the upper server. Thus, the system enables remote meter-reading.
In the system disclosed in document 1, communication between the slave and an upper device (e.g., the master and the upper server) is performed by power line communication using distribution lines as communication paths. If the power line communication is not available, wireless communication is used.
Document 1 also discloses that, in a situation where nodes (slaves and upper devices) are not arranged adjacent to each other, communication between the nodes is established by way of additional devices relaying wireless communication. For example, when maintenance terminals that are used for maintenance and inspection and perform wireless communication with the slaves and the upper devices are used as relay devices, communication paths between the slaves and the upper devices are ensured.
Recently, there has been proposed that the slave attached to the energy meter is configured to communicate with the electric appliance used in the facility in addition to the upper device. This configuration allows the electric appliance to visually indicate the energy consumption of the facility by displaying the measurement result of the energy meter, for example. Further, the configuration allows the electric power company to control the electric appliance by signals for the purpose of suppressing the peak of the energy demand (i.e., peak cut).
However, the boundaries of responsibility between the electric power companies and the consumers are given by the energy meters. When the slave attached to the energy meter has the function of communicating with the upper device and the maintenance terminal for maintenance and inspection, and additionally has the function of communicating with the electric appliance in the facility, undesired effects caused by traffic between different communications is not ignorable. In other words, occurrence of interference of the communication between the slave and the upper device and the communication between the slave and the electric appliance is undesirable.